Pheidole fortis Eguchi

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 31-34

Pheidole fortis Eguchi

Figs. 7a-7g

Pheidole fortis Eguchi , 2006: 118-120. Holotype: major, "Cat Cat (a trail to Mt. Phansipan), ca. 1300-1400 m alt., Sa Pa, Lao Cai, Vietnam, Eg02-VN-264", IEBR, examined; paratypes: 1 major & 19 minors, same data as holotype, IEBR, MHNG, MCZC, BMNH, FSKU & ACEG, examined.

Pheidole sp. eg-160. Bui & Eguchi 2003: 9 (checklist), Eguchi, Bui et al. 2005: 91 (checklist).

Other material examined: N. Vietnam: Vinh Phuc: Tam Dao N.P., 21°27'N, 105°38'E, 950 m alt. [Sk. Yamane]. Thailand: Chiang Mai: Doi Pui, ca. 1200 m alt., Doi Suthep-Pui N.P. [Eg01-TH-113]. Eguchi's informal species code " Pheidole sp. eg-160" has been applied to these specimens.

Worker measurements & indices: Major (data from the original description). - HL 2.12-2.23 mm, HW 1.79-2.05 mm, CI 84-92, SL 0.90-0.91 mm, SI 44-51, FL 1.33-1.39 mm, FI 67-78.

Minor (data from the original description). - HL 0.71-0.75 mm, HW 0.64-0.71 mm, CI 90-95, SL 0.79- 0.87 mm, SI 118-124, FL 0.92-0.97 mm, FI 134-144.

Worker description

Major. - Head in lateral view not or hardly impressed on vertex; head densely covered with short decumbent to subdecumbent hairs entirely; frons with longitudinal rugulae which reach posterolateral corner of vertexal lobes; frontal carina and antennal scrobe absent; clypeus with a median longitudinal carina; hypostoma with an inconspicuous median process and low or relatively developed submedian processes in addition to small lateral processes; antenna with a 3-segmented club; maximal diameter of eye almost as long as or longer than antennal segment X. Promesonotal dome with a much reduced prominence on its posterior slope; humerus not or very weakly produced laterad; the dome at the humeri as broad as or narrower than at the bottom. Petiole as long as postpetiole (excluding helcium); postpetiole massive. First gastral tergite rugoso-punctured at least in its anterior 1/3.

Minor. - Dorsum of head largely smooth and shining; preoccipital carina complete but weak dorsally; median part of clypeus almost smooth, usually with a conspicuous to weak median longitudinal carina; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye shorter than antennal segment X. Promesonotal dome smooth, in lateral view lacking a conspicuous prominence/mound on its posterior slope; humerus of the dome in dorso-oblique view hardly to weakly produced laterad; propodeal spine small, elongate-triangular. Petiole shorter than postpetiole (excluding helcium); postpetiole massive.

Recognition: This species is characterized among Indo-Chinese species by the following characteristics: in the major head densely covered with short decumbent to subdecumbent hairs entirely; in the major frons with longitudinal-oblique rugulae which reach posterolateral corner of vertexal lobes; in the minor promesonotal dome lacking a conspicuous prominence on its posterior slope; in the major and minor postpetiole massive. Pheidole fortis is similar to P. wroughtoni Forel (the type material housed in MHNG was examined), but well distinguished from the latter in which vertex and dorsum of vertexal lobe in lateral view forms an obtuse angle in the major, maximal diameter of eye longer than antennal segment X in the minor, and the posterior slope of promesonotal dome has a conspicuous prominence/mound in the minor. The minor of this species is similar to that of P. magna , but the minor of P. magna has a conspicuous prominence/mound on the posterior slope of promesonotal dome (see also Eguchi 2006).

Distribution & bionomics: Known from N. Vietnam and Thailand. This species inhabits open forests and forest edges, and nests in the soil (Eguchi 2006).